The German Gun Collectors Association has a Imman Meffert catalog reprint available for purchase. Click here to go to thier site and to view what they have to offer.
The following images are courtesy-
Click on the follwing lines to see the Meffert files in PDF
The following images were supplied by the Harlock family of Western New York State. They are of a shotgun made by Imman. Meffert and sold by Nowotny in Prague.